Like Keithmopar said ,71 was the last year for the 383 ,so if your seller is right on the year, then you`ve got a 400. The 400 is great too, just a bored out 383 essentially. The 383 and 400`s wind like small blocks with their short strokes. Not once I put in a 4.15" crank
A solid cam and lifters is a good upgrade.
No, I will stay with a Hyd cam until I stroke it
Good luck finding manifolds, they`ll probably cost you what a set of TTI`s will. Yeah, I have been figuring that out, most likely it will be a set of TTI's
I`d be sure you`ve got a good set of front brakes(disc) as well as the .89 torsion bars.The big blocks are heavier and if you`re used to driving a 318 you`ll feel the difference in the handling and braking.They also produce more power, so you`ll have to stop that thing somehow! I have a fully upgraded front disc / rear drum system with stainless braided power 73+ brakes, and I have never driven the car, it came off the trailer and went up on jackstands the same day, I have always driven high power pickup trucs, so haldling will most likely be better. As far as the torsion bars, I am going to try it with .87 bars, but will probably upgrade to .92 bars later.
If your rear end is not a 8.75, then it`d be time for a change too. Yes, I have an open 741 8 3/4", I will upgrade to a Posi 3.23 later.
I guess the thing to remember is that when you change from the sb to the bb you have to adapt the entire car to match. Good luck ,I hope we can help you out as you progress.